The present invention relates to gas fired apparatus for heating water and more particularly to a gas water heater/boiler comprising a cylindrical array of finned heat exchanger tubes into which penetrates a tubular gas burner for heating water or other fluid passing through the tubes.
The heat exchanger tubes are located vertically in the center of a cubical sealed casing which in turn is located inside a second sealed casing which forms the external body of the heating apparatus. The sealed space or forehearth separating the casings forms a passageway for fresh combustion air which ensures a very efficient thermal insulation of the heater. A blower is mounted within the forehearth which pressurizes the apparatus with fresh combustion air and thereby prevents any possible leak or circulation of combustion products.
The water heater/boilers of the present invention are designed for water pressure up to 160 pounds per square inch and a water temperature of 250 degrees Fahrenheit, thus making them suitable for commercial installations including swimming pool heater applications. The design permits indoor or outdoor installation. Due to the insulating effect of the sealed forehearth the water heater/boiler may be installed in a closet with combustible flooring or against closet walls with zero clearance and it can draw fresh air for combustion from outside or within the closet. The input range of the water heater/boiler, depending upon the particular size or model, is from approximately 250,000 BTU per hour to approximately 1,000,000 BTU per hour. However, the principles disclosed herein may be utilized for water heater/boilers having substantially smaller or greater BTU input levels.
One of the shortcomings of prior known water heater/boiler apparatus has been burner failure. In order to obtain high BTU input, high levels of heat from the burner are required. Excessive heat, however, frequently causes cracks, and hence failure, in metal tubular burners.
Another problem associated with conventional water heater/boiler systems is condensation of the flue products on the heat exchanger tubes and corrosion that is associated therewith.
A still further problem experienced by known water heater/boilers is the formation of mineral deposits on the inside of the heat exchanger tubes (also known as scaling or liming).
A still further problem of conventional water heater/boilers is heat loss and a resultant less than desirable thermal efficiency which translates into higher operating costs.
It is therefore desirable to provide a burner assembly for a gas fired water heater/boiler apparatus in which the burner is reinforced and the flame does not contact the outer surface of the burner assembly thereby ensuring cooler burner operation, longer burner life, and prevention of cracks or other premature
It is also desirable to provide a water heater/boiler apparatus in which the temperature of the combustion byproducts upon passing through the heat exchanger tubes is above the dew point thereby reducing the likelihood that condensation will occur on the heat exchanger tubes.
It is further desirable to provide a water heater/boiler apparatus in which the fluid to be heated travels through the heat exchanger tubes at a velocity sufficient to minimize liming of the tubes.
It is still further desirable to provide an insulated water heater/boiler apparatus that operates at high levels of thermal efficiency.